ZScript Discussion

[D2JK]

Is it possible to retrieve the player's current maximum health, when it has been modified in ACS using SetActorProperty and APROP_SPAWNHEALTH?

I'd like to avoid creating an intermediate inventory item to keep track of it, if possible.

Edit:

I forgot to mention: SpawnHealth() and GetSpawnHealth() won't work, as they keep returning "100" (the original max health before the modifications).

[Blue Shadow]

Didn't this help?

[D2JK]

Ah, right... I forgot I had already asked. Well, the thing is that I don't understand casting (my intention is to call this function from a weapon, not from the player class). Can you explain how to do that?

[Blue Shadow]

To do that, cast 'self' to 'PlayerPawn':

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let p = PlayerPawn(self); 

Then check for the validity of the cast by doing a null pointer check on 'p'.


Here is a working example:

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class RL : RocketLauncher
{
    Default
    {
        Weapon.SlotNumber 0;
    }

    States
    {
    Fire:
        MISG B 8 A_GunFlash;
        MISG B 12
        { // Fire a BFG ball if health is above max, otherwise fire a rocket.
            let p = PlayerPawn(self);

            if(p != null && health > p.GetMaxHealth())
            {
                A_FireCustomMissile("BFGBall");
            }
            else
            {
                A_FireCustomMissile("Rocket");
            }
        }
        MISG B 0 A_ReFire;
        Goto Ready;
    }
} 

[D2JK]

Many thanks! Now I get it.

By the way, in that if - check, is it possible for p to ever equal to null, in a case like this?

[Graf Zahl]

Currently not but you should always check anyway.

[Major Cooke]

Can something like this be done?

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// "MyActor" has an int variable PL.
Actor t = Spawn("MyActor",pos);

let s = t;

if (s)
{
    s.PL = 1;
}

Because this doesn't work. PL isn't recognized.

I ask because I have an array of Class<Actor>s to determine randomly which actor to spawn, and I haven't found a working solution to auto-resolve the class fully without requiring yet another cast to be around it.

Something tells me I need the list of actors to inherit from someone with the variable...

[Nash]

How much of ZScript will be overhauled in the short term? I just got done learning how to use the various macros used to export stuff to ZScript for my custom native fields and functions (for my standalone game) but if they're going to change soon, I think I should just hold back from working any further...

[Graf Zahl]

Because this doesn't work. PL isn't recognized.

Of course not. If you need a common variable for a set of actors they need to inherit from a common base class and the variable needs to be of the base class's type. 'let s = t;' will give s the same type as t, not the type of the actual object t points to. That cannot be done at compile time.

[ZZYZX]

Note: question to Graf, Cooke as the 2nd best ZScript expert already said he doesn't know.

This article http://zdoom.org/wiki/ZScript_variables
Claims that single-quoted strings are something called "names".

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const con4 = 'A name it is.'; //name

How do I define a char then?
For example I'd want to write my own int parsing function (for whatever, this is just a theoretical example). I'd want to get integer value of char '0' and subtract it from chars provided these chars are between 0 and 9.
I also once had a random coloring function that basically appended a \c escape sequence plus Random('A', 'V') on top of it.
How do I do this in ZScript?

[Graf Zahl]

At the moment you can't. The constant parser as it is now is too limited for that - this is still the original as Randi implemented it and it's suffering from several limitations. Eventually this will have to be redone using the compiler backend to resolve the expressions but this is going to be a bit of work.

[Nash]

I have a problem.

I want a bunch of new variables that I've made to be accessible by EVERYTHING - monsters AND players included. "extend class Actor" is not possible.

I could probably create ie

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class Z_Actor : Actor
{
    int customVar;
}

And have my monsters inherit Z_Actor instead of Actor. But that will only work for monsters.

What about players? I want my PlayerPawns to have access to customVar too.

The ONLY way I see of doing this is to now make a copy:

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class Z_PlayerPawn : PlayerPawn
{
    int customVar;
}

... what this means is that I now have to define the variables twice, one for every generic actor, and one more for the players. This is really clumsy. And I plan to add MANY variables. It will become tedious.

My goal is to just declare (lots) of new variables that EVERY actor class could use.

It would've worked if only "extend class Actor" was supported but well, it doesn't.

Help?

[ZzZombo]

Yeah, I've asked already why we can't extend/override existing definitions, but got no reply.

[Graf Zahl]

You can't extend Actor by new variables because they cannot propagate to already derived subclasses. If you wanted to add a custom variable, *ALL* subclasses of Actor would need to have it, even those which have already been created and where other variables are already occupying the same slot. And for native subclasses this is not solvable at all.

It's also highly non-trivial on the implementation side because those added variables couldn't be regular members of the object, they'd have to be stored elsewhere with very costly access methods.

[ZzZombo]

But does this hold for functions? So you could override, say, AActor::Die().